The present invention relates to an air intake noise suppressor for reducing noise generated by intake air sucked into an internal combustion engine such as, for example, an internal combustion engine for use in a vehicle.
As one of such air intake noise supporessors, there is known an air intake noise supporessor in which a branch pipe (a resonance pipe) having its tip end closed is branched from a midway of an intake air passageway so that air intake noise in a particular frequency region can be attenuated by the air within that branch pipe being resonant with oscillation of intake air flowing through the intake air passageway, and such an air intake noise suppressor is disclosed, for example, in Japanese Laid-Open Utility Model Publication No. 58-53846 (1983).
In this air intake noise supporessor, the branch pipe branched from an intake pipe extends externally nearly at right angles to the intake pipe, and the tip end of the branch pipe is inserted into an exhaust pipe.
However, in the above-described air intake noise suppressor in the prior art, since the whole length of the branch pipe projects laterally from the intake pipe, and moreover, since the length of the branch pipe is determined by the intended resonance frequency and cannot be shortened arbitrarily, sometimes difficult problems were encountered with respect to a place for mounting a branch pipe and a method for supporting the same, especially in the case of an internal combustion engine for use in a vehicle such as a motorcycle or the like in which a place for mounting the air intake noise suppressor is limited.